This invention is in the field of equipment for end-of-assembly line testing of seats, in particular vehicle seats with manual and/or power adjustments.
All automotive seats manufactured today include adjustment features, whereby the operator can adjust one or more of the seat cushion, seatback and head rest.with manual controls or electrical switches controlling mechanical or power adjustment mechanisms built into the seat. The more xe2x80x9cpremiumxe2x80x9d the vehicle in which they are installed, the more adjustment features the seats tend to have. Seats that are purely manually-adjusted, purely power-adjusted, or a hybrid of manual and power adjustments are known.
Referring to FIG. 1, adjustable seats 12 are typically completed on an assembly line, moving down and off the line on a specialized shipping pallet 14. It is common to palletize two seats on a single pallet as shown, for simultaneous testing. At or near the end of the line, the adjustable parts of the palletized seats are typically inspected and tested by a human operator using a combination of physical manipulation of the seat""s manual adjustment controls, such as levers, and/or power adjustment switches such as 13b, 13c. In the example of FIG. 1, seatback 12b and seat cushion 12c are power adjustable.
In a typical end of the line seat testing station, a palletized seat arrives at the station and is locked into a fixed testing position by a xe2x80x9cpallet pusherxe2x80x9d or similar, known positioning device. If the seat has power adjustments, the operator plugs a power supply tether into a wiring harness connector built into the seat. This wiring harness connector is wired into the various adjustment motors, switches, and control modules in the seat; when the seat is installed in a vehicle, the wiring harness connector is plugged into a mating harness on the vehicle which supplies power, control signals and data communication from various systems on the vehicle. The electronic tether plugged into the wiring harness connector at the end-of-line testing station supplies power, control signals and data communication so that an operator can run the powered seat through its various adjustments.
As the operator runs a seat (manual or powered) through its adjustments at the testing station, end of line testing apparatus verifies basic seat adjustment functions performed by the operator by providing a signal corresponding to various adjustment positions or end-of-travel limits. There are generally two types of seat testing system: xe2x80x9cinternalxe2x80x9d and xe2x80x9cexternalxe2x80x9d.
The xe2x80x9cinternalxe2x80x9d type tests powered seat component function through the tether connection to the wiring harness connector, communicating through the tether with a computer software or PLC-type controller to monitor and verify internally-generated seat adjustment parameters such as motor speed, motor stall current, direction of motor travel, switch function, etc. In more sophisticated seats with built-in xe2x80x9cseat modulesxe2x80x9d, other internal seat parameters can be tested through the wiring harness connector and seat module via the tether, for example the function of seat heating equipment. A problem with this xe2x80x9cinternalxe2x80x9d, tether-type testing apparatus is that an internal failure of an adjustment mechanism, for example a premature motor stall or a broken or improperly coordinated connection between a motor and the part being adjusted, can result in a xe2x80x9cpassxe2x80x9d indication to the operator on a display screen while the actual seat adjustment is inadequate.
The xe2x80x9cexternalxe2x80x9d type of seat testing apparatus can be used for either manual or powered seats, and comprises an external array of limit.switches connected to wands, probes or contact arms to generate a signal of physical seat position when contacted or moved by an associated part of the seat. For example, when the operator moves or runs the seatback to its full-recline position, the seatback will contact and move a limit switch actuator to generate a full-recline verification signal to the operator. This signal is typically in the form of a light display visible to the operator.
Referring to FIG. 2, one example of a prior art end-of-line tester is generally illustrated at 20, comprising contact arms 22a-22d mounted on a frame 26. Frame 26 in turn is supported on a sliding base 28 whose position can be moved toward and away from seat 12 on a track or rail 30 by a powered pusher mechanism 32 of known type. Base 28 may slide on rail 30 via carriage portions 28a. 
Contact arms 22a-22d end in limit switches 24a-24d, positioned for contact with associated portions of seat 12 in their respective fully-adjusted positions. For example, uppermost limit switch 24a is located to be engaged by headrest 12a when the seat is either fully reclined or fully aft (depending on the seat""s adjustability and the preferred test parameter); limit switch 24b should be contacted by the upper seatback 12b; limit switch 24c should be contacted by the lower seatback 12b, and, lowermost limit switch 24d should be contacted by seat cushion 12c in the fully aft position.
Once tester 20 is pre-positioned with limit switches 24a-24d as described above, the operator (not shown) typically will lean over seat 12 and operate its adjustment controls (such as 13b, 13c shown in FIG. 1) to recline seatback 12b, and to move seat cushion 12c fore and aft. When seatback 12b reaches its full-recline position (shown in broken lines) it should contact certain limit switches to trigger a xe2x80x9cpassxe2x80x9d signal to the operator in known fashion. Having been successfully tested, seatback 12b is then brought forward to its full-up position, and the operator translates seat cushion 12c rearwardly until it reaches a full-aft position (broken lines) in which limit switch 24d generates a xe2x80x9cpassxe2x80x9d signal.
It is also known to use test equipment such as that shown at 20 to check for the xe2x80x9cpresencexe2x80x9d of major seat parts such as seatback 12b and seat cushion 12c, for example by pushing tester 20 into contact with seat 12 in its at-rest position (solid lines) and generating xe2x80x9cpresencexe2x80x9d signals upon contact of limit switches 24a-24d with their associated seat portions.
One problem with xe2x80x9cexternalxe2x80x9d prior art testers of the type shown in FIG. 2 is that they can be xe2x80x9cfooledxe2x80x9d by operators who simply press the limit switches to generate a xe2x80x9cpassxe2x80x9d signal whether or not the seat parts have been successfully adjusted. Another problem with such testing apparatus is that it is limited to testing static seat positions, for example the xe2x80x9cpresencexe2x80x9d of major parts and the xe2x80x9cfull-aftxe2x80x9d or xe2x80x9cfully-reclinedxe2x80x9d limits of travel. Additionally, the overall number of seat adjustment functions capable of being tested by such apparatus is limited by the need to position contact arms and limit switches at every point where a desired presence or travel limit should be sensed. A further problem is the need to frequently re-position such testers and their contact arms. A tester configured for contact with a particular seat model cannot be used for other models without adjusting the number and placement of the contact arms; a tester configured for xe2x80x9cpresencexe2x80x9d testing must be reconfigured for xe2x80x9cadjustmentxe2x80x9d testing.
The present invention is an end of line tester apparatus, system, and method which is capable of testing a virtually unlimited number of seat adjustment functions; which cannot be fooled by an operator; and which cannot mistakenly verify (or fail to verify) a seat part adjustment due to internal error of a seat adjustment mechanism. The inventive tester is further capable of measuring not only the presence and end-of-travel limits of the adjustable seat parts, but further can measure a full range of both seat motion and internal adjustment function in real time.
In its broadest form the invention comprises an array of optical ranging type position sensors located behind the seat assembly at the test station, with one or more sensors associated with one or more target portions of the seat to measure a particular adjustment. In a preferred form, the optical sensors are infrared or laser distance-measuring devices of known type, although other known types of sensors can be used, for example radar sensors and other non-contact ranging/sensing devices. In a further preferred form one or more of the sensors may be dedicated to determining the presence or absence of optional seat parts, such as armrests. Sensors primarily used for measuring the adjustment of certain seat parts can also be used to establish their presence at the beginning of the test cycle.
In a further form of the invention useful for powered seats, the optical sensor array operates in a closed loop with internal seat function testing equipment. In the preferred form the output of the optical sensor array communicates with an internal function tester, for example a computer or programmable logic controller (PLC) communicating by tether with internal seat adjustment mechanisms through the seat""s wiring harness connector. In closed loop fashion the optical sensor output and real time motor function are compared as the respective seat part is adjusted, and operator inputs to the internal function tester such as seat model or type can be verified by checking for the presence of standard or optional components which should be found on the operator-entered model/type.
Another advantage of the present invention is the ability of the optical sensor array to be zeroed out for each seat assembly to accommodate positioning differences due to different types of seats, variations in the pallet/conveyor system, etc. In a closed loop system with internal function testing, the optical sensor array may be zeroed corresponding to internal zero measurements at the beginning of the test cycle.
For powered seats, the closed loop system also gives the operator the ability to isolate specific motor function/performance, allowing accurate diagnosis of internal errors via external sensing/verification. By externally verifying the internal testing of seat adjustment and position taken through a powered seat""s wire harness connector by tether, the optical sensor array provides a comprehensive, virtually mistake-proof system and method for making sure that power-adjustable seats are fully functional when they come off the assembly line. These and other features and advantages of the present invention will become apparent upon further reading of the specification in light of the accompanying drawings.